According to Wikipedia, a duvet day is a day off from work you take when you’re not sick and don’t have other reasons for staying at home, but just feel like a break. Some people apparently have the right to such days in their contracts.
I wish we were allowed such leaves. All of us from the little ones in school to the bonded laborers.
It would be so good to have a day off everything officially (without making a lame fake excuse). Just you and your computer (of course with high-speed internet connection, oh yes that’s like a basic necessity) with all the high carb and calorie rich food in your duvet in your most comfortable pair of shorts. HEAVEN.